Diamond drill bit



Jan. 17, 1956 F. BRUCE DIAMOND DRILL BIT Filed Oct. 5, 1953 INVENTOR. FVqyd Bruce %?2 G M ATTORNEYS United States Patent The invention described herein may be manufactured and used by or for the Government for governmental purposes, without payment to me of any royalty thereon. The present invention provides improvements in rotary drills as used for the formation of holes in rock, granite,

stone, and other hard materials, and more particularly it has reference to improvements in non-coring drill bits of that type known generally to the trade as diamond drills and which are of that particular kind designed to cut away all of the material within the circumference of the face of the bit, thus to eliminate the necessity for any provision of means for the passage of a core.

An object of the present invention may be said to be the provision of a high speed rotary face bit having a central-concave recessed surface located coaxially of the bit andsurrounded by a convex surface, both the concave and convex surfaces having diamond cutters so set there- .in that the entire area of the surface acted on by the bit will becut away and ground up for removal by an outflow of-water that is delivered under pressure through the drill rod to the face of the bit for lubrication of the cutters.

Additional objects of the present invention may be said to comprise improved access ,of drill water to the working face of the bit for removing all of the cuttingsand to lubricate the bit, and improvements in the construction of the center portion of the bit for improving the cutting actionof such center portion of the bit.

Other objects and advantages of the present construc- .tion will become apparent as the description proceeds,

and the features of the construction willbe defined in particularity in the appended claims.

Before proceeding with a detailed consideration of the present construction, it may be pointed out that previous to the present construction, all drill bits of the non-coring type have had a weakness in that the cutting diamond -that is centrally disposed, or approximately centrally disposed, becomes crushed in service because of the absence of itranslatory motion and because of such crushing is unable to cut the rock, which becomes crushed off in the resulting bit of the diamond cutter by the weight of the drill. Also, in previous constructions, the waterentrance part is ,set customarily to one .side of the'bit axis, thus -causing the water to flow to the ,short sideof the b1t,

thus resulting in crushed rock not being washed away .from the axis of the bit. Rotation of the bit with the away all crushed stone from the bit;

4. A large elongated-diamondis set at the apex of the core and-isplaced at or adjacent to the axis of the bit;

2,?3L23b Patented Jan. 17, 1956 5. The special apical cutting diamond wedges fragments from the apex of the conical core, which are picked up by the liquid stream and carried away.

The foregoing advantages and objects of the present construction will be understood more readily by reference to the accompanying drawings, in which:

Fig. 1 represents a side elevation of the improved drill bit;

Fig. 2 is a vertical sectional view therethrough;

Fig. 3 is a bottom view of the bit;

Fig. 4 is a side elevation of the bit partially in vertical section, the view indicating the bit in operative or cutting position; and

Fig. 5 is a fragmentary top plan view of Fig. 1.

Referring more particularly to the drawings, the improved drill bit comprises ;a head or drilling portion A, comprising approximately the lower end half of the bit as seen in Figs. 1, 2, and 4, and an exteriorly threaded neck or shank portion B, comprising the upper half portion, and whereby the bit may be mounted for a drilling operation on the end of an internally complementarily threaded drill rod C. This drill rod, in addition to being internally threaded, is tubular for conveying .water to the bit.

As will be seen from the drawings, the bit is hollow, thereby providing an internal water-supplying chamber 10, which has direct communication with the lower end of the drill rod, it being understood that theqlatterserves as the medium through which water is delivered under pressure to the bit to lubricate the cutters, and to wash away the sludge as the material acted on is ground up by the cutters under the rotary action of the head. The

water supplied to the head through the drill rod C is delivered to the cutting face of the bit through a crescentshaped outlet or opening 12 which will be referred to in greater detail hereinafter.

The headportion A of the drill bit is substantially circular in cross section, as is also the neck or shank portion B, and it will be noted that the neck portion B is of slightly smaller diameter than the head portion A, thus forming an upwardly-facing, annular shoulder 14 about the bit. This reduction in the diameter .of the neck-portion of the bit enables the formation of a uniformlyflush junction between the head portion of the bit .and the drill rod.

Before going into a detailed description of the bit, it may be noted that there are several important advantages in not being requiredto take a corein a-boring or drilling operation, where a core is not required to be taken.

It will be understood that any hole, even small, will allow acore to pass through into the central .water passage of the bit, which passage is under water pressure while drilling is going on and the fiow of water is toward the face of the bit. This small core, coming up through the center hole, breaks up, with the result that the water discharge holes of the bit become clogged, and proper lubrication of the face of the bit thus is prevented, with the result that the bit becomes burned and considerable loss of time is experienced in correcting resulting damage and replacing the bit. The present construction avoids thisdifiiculty and objection.

.As has been indicated above, the present improved bit Before detailed reference to the improved water distribution system is made, further detailed reference will be made to the working face ofthe bit. As will be seen from the drawings, this working surface is disposed centrally and coaxially of the bit and comprises a sectional-Work or cutting-chamber composed of a conically tapered, concave upper section 16 which registers with and surmounts a substantially cylindrical lower section 18, with which the upper conical section 16 merges along a peripheral juncture line 19. Also this lower section 18 merges along a substantially circular cutting crown 20 with the outer periphery of the bit.

The working parts of the bit are the cutting crown 2t), and the surfaces forming the superposed cutting sections 18 and 16, the latter section being approximately on a 45 angle and converges into an apex pointed into the bit. The crown 20 is similar to that of standard coring bits, except for being thicker for additional strength.

As will be seen from the drawings, a feature of the present invention comprises the provision of a large number of diamond cutters 22 which are set closely together in the peripheral surfaces of the sections 16, 18, also in the crown 20 and the lower portions of the outer peripheral surface 24 of the bit section A. The location and setting of these diamond cutters in the various surfaces is of importance, particularly as it applies to those located near the apex of the central conical cutting section 16. Heretofore, it has been accepted as factual that it is impractical to locate diamond cutters near the axial center or apex of any conical recess, and for that reason, bits employing such a recess have been provided most generally with a central hole for the passage of a core, and the diamond cutters have been set closely around the hole to cut out the core.

In such previous instances, however, when diamond cutters have been set close to or at the apex of the recess, as is the case with drill bits of the non-coring type, as has been noted above, the cutting diamond that is centrally disposed, or approximately centrally disposed, that is, which is at or close to the apex of the recess, becomes crushed in service and thus is rendered inoperative to cut the rock which becomes crushed off in the bit by the weight of the drill. For such reason, as has been pointed out above, it has not been found to be practical in such prior constructions to locate diamond cutters near the axial center or apex of a conical recess, so that bits employing such a conical recess have been provided most generally with a central hole for the passage of a core, and the diamond cutters have been set closely around the hole to cut out the core.

It now has been found, in accordance with the present invention, that this previously encountered disadvantage is obviated by the employment of a large and massive elongated cutting diamond such as that which is designated on the drawings by numeral 26, which is placed approximately at the apex of the conical cutting surface of the section 16 with the axis of the bit passing through this apical cutting stone 26 but adjacent to the upper end thereof, the massive elongated diamond 26 being set with its longitudinal axis on the same angle to the axis of the bit as that of the slope of the conical section, so that the stone 26 lies parallel to the surface of the conical surface.

The multitude of small diamond cutters 22 are set on circumferences of separate concentric circles, the radii of which gradually lengthen from adjacent to the apex of the conical section 16 to the line 19 thereof which defines the periphery of the base of the conical section 16 as well as the merging line of this section 16 with the cylindrical lower section 18, that is, such concentric circles may be regarded as being defined by the intersection of a plurality of planes normal to the axis of the drill with the interior surface sections 16 and 18. Each of these diamonds is required to take only a small amount of pressure so that the diamond loss is materially reduced and the rate of advancement of the bit is found to be entirely satisfactory in practice.

The present construction is characterized, in addition to the massive apical cutting stone 26, by the improved Water distribution system which includes a curved or substantially crescent-shaped opening or port 12 which communicates with a crescent-shaped water supply duct 28 which communicates in turn with the bottom of water supply chamber 10 in the shank portion B of the bit. This crescent-shaped opening or port 12 supplies water from the chamber 10 to the working area of the bit around the massive apical cutting stone 26 for carrying away cuttings and lubricating the bit. The drill Water has no escape except across the working face of the bit, thence through substantially equally disposed channels 30 extending from the juncture 19 of the sections 16 and 18 around the crown 2% of the bit and thence upwardly along the outer periphery of the bit. In practice, three approximately equally spaced channels 30 are provided.

The bit operates by cutting a core 32 with the crown portion 20 of the bit, grinding the core away in the conical section 16 until it is very small, and then wedging off the remainder by action of the massive elongated apical cutting stone 26. The drill water coming through the opening 12 catches the portion of the core 32 as it is wedged off and washes it away. Also, drill water coming through the curved opening 12 washes across the apical stone 26, and over the entire face of the bit, removing cuttings and lubricating the bit, the cuttings being washed out from the central cutting sections 16 and 13 of the bit through the peripheral channels 30. This drill water cools the cutting diamonds below any danger of destructive overheating and lubricates the drill.

The foregoingly-described construction of the improved drill bit of the present invention represents a preferred embodiment of the features of novelty of the present construction which importantly combine the provision of a conical centrally disposed cutting section in the bit, at the apex of which section and coincident with the axis of the bit is positioned a massive elongated cutting diamond which is placed in the conical cutting section on the same angle as that of the surface defining the said conical section, so that the slope of this elongated cutting diamond is coincident with the slope of the conical section, together with the curved or substantially crescent-shaped water discharge port which is located adjacent to this massive apical cutting stone and substantially encloses the same. The specific srtuctural details of the bit such as the thickness of the crown and the size and arrangement of the relatively small cutting stones distributed over the Working surfaces of the bit may be varied as determined by particular service conditions without departing from the inventive concept, and accordingly, it will be understood that it is intended and desired to embrace within the scope of the invention such modifications and changes as may be necessary to adapt it to varying conditions and uses, as defined by the appended claims.

Having thus described my invention, what I claim as new and wish to secure by Letters Patent is:

1. A rotary diamond drill bit adapted to be mounted in a rotary drill rod, which comprises a neck portion and a cutting head portion, the former being hollow and including a Water-supplying chamber, the latter having cutting surfaces including a cutting crown and a centrally disposed sectional work-chamber concentric with the longitudinal axis of the drill rod and composed of a pair of superposed communicating sections defining a peripheral juncture therebetween, which sections are respectively a substantially cylindrical section adjacent to the cutting crown and an upper conical section having an apex substantially coincident with the longitudinal axis of the bit, the conical section registering with and merging in a peripheral juncture with the cylindrical section, and cutting stones substantially uniformly distributed over the cutting surfaces of both sections and the crown and including a massive elongated apical cutting stone disposed substantially at the apex of the conical section coincident with the longitudinal axis of the bit and having its longitudinal axis positioned on the same angle to the longitudinal axis of the bit as the slope of the conical surface of the conical section, the conical section being provided with a crescent-shaped water-discharge opening adjacent to and substantially concentric with the apex of the section and partly enclosing the massive elongated apical cutting stone and communicating with the water-supplying chamber in the neck portion of the bit for directing drill water across the said massive stone and the entire cutting surfaces of the bit, the said lower section and crown surfaces of the bit being provided with a plurality of substantially equally spaced channels in the lower cylindrical section extending from the peripheral juncture between the upper conical section and around the cutting crown of the bit and thence upwardly along the outer periphery of the cutting crown for leading water from the said curved dis charge opening around the crown to the outer periphery of the bit.

2. A rotary diamond drill bit as claimed in claim 1, wherein the cutting stones include in addition to the said massive apical cutting stone, a multitude of small cutting stones uniformly distributed on the surfaces of the sections and of the crown, the said small stones being set on circumferences of separate concentric circles, the radii of which circles gradually lengthen from adjacent to the apex of the conical section to the peripheral juncture between the conical section and the cylindrical lower section, the said concentric circles being defined by intersections of a plurality of planes normal to the longitudinal axis of the drill bit with the surfaces of the said conical and cylindrical sections.

3. The rotary diamond drill bit structure as claimed in claim 1, wherein the crescent-shaped water-discharge opening communicates with a crescent-shaped water supply duct communicating with the water-supply chamber in the neck portion of the bit, the said crescent-shaped water supply duct and opening supplying water from the said chamber into the said sections around the massive apical stone and adjacent thereto for carrying away cuttings and lubricating the bit, the water having no substantial escape except across the surface of the conical section between the circularly disposed cutting stones thereof, thence through the said spaced channels, the said water removing core cuttings from the section and cooling the cutting stones below any danger of destructive overheating While lubricating the drill.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,632 Zublin Mar. 10, 1953 2,217,889 Carpenter et al. Oct. 15, 1940 2,264,617 Carpenter et al. Dec. 2, 1941 

